高糖波动诱导氧化应激及内质网应激损伤胰岛β细胞功能

Impairment of pancreatic islet β cell function induced by intermittent high glucose through oxidative and endoplasmic reticulum stress： experiment with rat pancreatic islet β cells

目的评价波动性高糖对胰岛β细胞胰岛素合成及分泌功能，及对氧化应激和内质网应激的影响。方法检测波动性（IHG）和持续性高糖（SHG）刺激后INS-1细胞合成及分泌胰岛素的功能，并测定细胞内过氧化物还原酶（PDX）-1、8-OHdG、NT及ATF-4等表达。结果经过72h孵育，IHG组INS．1细胞的胰岛素分泌指数明显低于SHG组（对照：1．67±0．23，SHG：1．31±0．04，IHG：0．64±0．11，P〈0．05），且是时间依赖性的；IHG和SHG组较对照组细胞内胰岛素含量显著低[对照（12．37±0．37）μU／μg，SHG（11．08±0．03）μU／μg，IHG（10．91±0．14）μU／μg，P〈0．05）]，而且胰岛素和PDX-1的mRNA表达亦明显低；IHG组INS-1细胞较SHG组和对照组的8-OHdG、硝基酪氨酸含量以及ATF-4表达明显高。结论波动性高糖较持续性高糖更能损伤胰岛β细胞功能，这与波动性高糖增高胰岛B细胞内氧化应激及内质网应激水平密切相关。

Objective To investigate the effect of intermittent high glucose （IHG） on the pancreatic islet β-cell function and mechanism thereof. Methods Rat pancreatic islet β-cells of the line INS-1 were cultured and randomly divided into 3 groups： IHG group exposed to fluctuating concentrations of glucose, stable high glucose （SHG） group exposed to 16. 7 mmol/L glucose, and control group exposed to normal concentration （5.5 mmol/L） glucose. 24, 48, and 72 hours later radioimmunoassay was used to detect the insulin secretion index （ISI）. 72 h later, the concentration of insulin in the cells was detected with radioimmunoassay. The contents of oxidative stress markers, nitrotymsine （NT） and 8-hydrnxy-2- deoxygnanosine （8-OHdG） were detected. Real-time PCR was used to detect the mRNA expression of peroxiredoxin 1 （ PDX-1 ）, ATF-4, one of the transcription factors of the family bZIP, and insulin. Western blotting was used to detect the protein expression of ATF-4. Results The ISI of the IHG and SHG groups decreased time-dependently, The ISI of IHG and SHG groups were 0.64 ± 0. 11 and 1.31 ± 0.04 respectively, both significantly lower than that of the control group （ 1.67 ±0. 23, both P 〈 0. 05 ）. The intracellular insulin contents of the IHG and SHG groups were （ 10. 91±0. 14） and （ 11.08 ± 0. 03 ） μU/μg respectively, both significantly lower than that of the control group [ （ 12. 37 ±0. 37 ） μU/μg, both P 〈 0. 05 ]. The intracellular concentrations of 8-OHdG and NT of the SHG and IHG groups, were significantly higher than those of the control group （ all P 〈 0. 01 ）, and those of the IHG group were significantly higher than those of the SHG group （ both P 〈 0. 05 ）. The mRNA and protein expression levels of ATF-4 of the IHG group were all significantly higher than those of the control group （all P 〈0. 05 ） and those of the IHG group were significantly higher than those of the SHG group （ both P 〈 0. 05 ）. Conclusion IHG and SHG induce severe impairment in pancreatic islet β cell functions, especially IHG, which is closely associated with the aggravation of oxidative stress and endoplasmic reticulum stress triggered by intermittent high glucose.